Sheet convey apparatus

ABSTRACT

A sheet convey apparatus includes a pile board, sheet air blowers and a leveling foot, and first, second, and third suction ports. A plurality of sheets are to be stacked on the pile board. The sheet air blowers and the leveling foot supply air between first and second sheets which are the first and second when counted from an uppermost one of the sheets stacked on the pile board, to separate the first sheet from the second sheet. The first suction ports are supported to be movable in a direction of sheet thickness, and chuck and hold a trailing edge of the separated first sheet to lift upward the separated first sheet. The second suction ports are supported to be movable in a sheet back-and-forth direction, and chuck and hold a more sheet leading edge side than a portion chucked by the first suction ports of the first sheet transferred from the first suction ports, and convey the first sheet forward. The third suction ports are supported to be movable in the sheet back-and-forth direction, and chuck and hold the trailing edge of the first sheet transferred from the first suction ports, and convey the first sheet forward.

BACKGROUND OF THE INVENTION

The present invention relates to a sheet convey apparatus which is usedin a sheet feeder or the like for a sheet-fed offset rotary printingpress and serves to chuck stacked sheets one by one from the uppermostone and feed it forward.

Conventionally, a sheet convey apparatus has been proposed as shown inJapanese Utility Model Laid-Open No. 5-51835, which comprises a suctionport holder which chucks the trailing edge of the uppermost one ofstacked sheets and upper and lower cams and front and rear cams whichare fixed parallel to each other to cam shafts rotatably driven bymotors. In the conventional convey apparatus, the suction port holder ismoved downward by the cam action of the upper and lower cams to chuckthe trailing edge of a sheet, and moved upward. The sheet is thenconveyed to a feed roller by the cam action of the front and rear cams.

FIGS. 6A and 6B show another conventional sheet convey apparatusdescribed in Japanese Utility Model Publication No. 3-24511. Referringto FIG. 6A, a sheet convey apparatus 101 comprises a pile board 11 onwhich a plurality of sheets 10 are to be stacked, a pair of firstsuction ports 12 which are supported to be movable in the widthwisedirection of the sheets 10 stacked on the pile board 11, and a pair ofsecond suction ports 13 which are supported to be movable in theback-and-forth direction (a direction of arrows A-B) of the sheets 10staked on the pile board 11. As shown in FIG. 6B, the pair of suctionports 13 are attached to the two ends of a support shaft 14 extending inthe widthwise direction (a direction perpendicular to the direction ofthe arrows A-B) of the sheets 10. The support shaft 14 is supported tobe movable in the direction of the arrows A-B through a cam shaft (notshown) which is axially supported by a sucker frame 15 and driven torotate by a motor, and a cam (not shown) which is axially mounted on thecam shaft. Suction air is supplied to the suction ports 12 and 13 froman intake device (not shown) through a hose.

Sheet air blowers 16 serving as an air blowing member blow separationair to the sheets 10 stacked on the pile board 11 from behind so thestacked sheets 10 separate smoothly. When air is supplied from the sheetair blowers 16 to move a sheet 10 slightly upward, the moved sheet 10 isreliably chucked by the suction ports 12.

A leveling foot 17 serving as an air blowing member reciprocates betweena standby position (FIG. 6A) and an operative position (FIG. 8A) andenters between an uppermost sheet 10A chucked by the suction ports 12and the sheets 10 under it to press the sheets 10. Simultaneously, theleveling foot 17 blows separation air to separate the uppermost sheet10A entirely from the sheets 10 under it. When the sheet which isconveyed as it is chucked by the suction ports 13 is released, holddownwheels 18 and a forwarding roll 19 catch the released sheet and feed itonto a feeder board 20.

Sheet convey operation in the conventional sheet convey apparatus willbe described with reference to FIGS. 6A and 6B to FIGS. 12A and 12B.First, as shown in FIGS. 6A and 6B, the sheet air blowers 16 blowseparation air momentarily to the sheets 10 stacked on the pile board 11from behind to separate a sheet 10 stacked on the top. Then, the firstsuction ports 12 to which suction air is supplied from the intake device(not shown) move downward to chuck the trailing edge of the uppermostsheet 10A which is separated by the sheet air blowers 16. The firstsuction ports 12 then move upward to lift the trailing edge of the sheet10A, as shown in FIGS. 7A and 7B. In this state, as shown in FIGS. 8Aand 8B, the leveling foot 17 enters between the uppermost sheet 10A anda sheet (the second sheet from the top) 10 under the sheet 10A to urgethe sheets 10. Simultaneously, the sheet air blowers 16 supplyseparation air to separate the uppermost sheet 10A entirely from thesheets 10 under it.

Subsequently, the intake device (not shown) supplies suction air to thesecond suction ports 13 to chuck, by the second suction ports 13, adownstream portion in the sheet convey direction (the direction of thearrow A) of the trailing edge of the separated uppermost sheet 10A.After that, when supply of suction air to the first suction ports 12 isstopped immediately, the sheet 10A chucked by the first suction ports 12is released and transferred from the first suction ports 12 to thesecond suction ports 13, as shown in FIGS. 9A and 9B. The second suctionports 13, while chucking the uppermost sheet 10A, are accelerated to aconvey speed as they translate in the sheet convey direction (thedirection of the arrow A), as shown in FIGS. 10A and 10B. When theleading edge of the sheet 10A which is conveyed by the second suctionports 13 is caught by the holddown wheels 18 and forwarding roll 19, asshown in FIGS. 11A and 11B, supply of the suction air to the secondsuction ports 13 is stopped to release the sheet 10A chucked by thesecond suction ports 13. The sheet 10A which is released from the secondsuction ports 13 is fed onto the feeder board 20 by the holddown wheels18 and forwarding roll 19, as shown in FIGS. 12A and 12B.

In the former apparatus described above, the sheet is conveyed as itstrailing edge is chucked by one suction port holder. The leading edge ofthe sheet which is not chucked by the suction port holder comes intocontact with a sheet under it during conveyance. Thus, sheet conveyancecannot be performed smoothly. As the leading edge of the sheet cannot becaught by the feed roller, poor sheet-feeding readily occurs. This isconspicuous particularly with a large-sized sheet.

In the latter apparatus described above, when the trailing edge of thesheet 10A is released from the first suction ports 12, it may be broughtinto tight contact with a sheet 10 under it, as shown in FIGS. 13A and13B, by the negative pressure produced by the separation air from theleveling foot 17 which is generated under the released sheet 10A. Inthis case, since the sheet 10A is conveyed in contact with the sheetunder it, the sheet 10A cannot be conveyed smoothly. Also, as theleveling foot 17 is no longer inserted between the sheet 10A and thesheets 10 under it, the separation air from the leveling foot 17 passesabove the uppermost sheet 10A. As a result, the trailing edge of a sheet10B which has been fed out immediately before the sheet 10A is blown up,so the sheet 10B thus flutters or waves to cause poor sheet-feeding.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a sheet conveyapparatus which conveys a sheet smoothly to prevent poor sheet-feeding.

In order to achieve the above object, according to the presentinvention, there is provided a sheet convey apparatus comprising a pileboard on which a plurality of sheets are to be stacked, air blowingmeans for supplying air between a first sheet and a second sheet whichare the first and the second when counted from an uppermost one of thesheets stacked on the pile board, to separate the first sheet from thesecond sheet, first chucking means, supported to be movable in adirection of sheet thickness, for chucking and holding a trailing edgeof the separated first sheet to lift upward the separated first sheet,second chucking means, supported to be movable in a sheet back-and-forthdirection, for chucking and holding a more sheet leading edge side thana portion chucked by the first chucking means of the first sheettransferred from the first chucking means, and conveying the first sheetforward, and third chucking means, supported to be movable in the sheetback-and-forth direction, for chucking and holding the trailing edge ofthe first sheet transferred from the first chucking means, and conveyingthe first sheet forward.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of a sheet convey apparatus according to thefirst embodiment of the present invention;

FIG. 1B is a plan view of the apparatus shown in FIG. 1A;

FIG. 2 is a plan view of a sheet convey apparatus according to thesecond embodiment of the present invention;

FIG. 3 is a plan view of a sheet convey apparatus according to the thirdembodiment of the present invention;

FIG. 4 is a plan view of a sheet convey apparatus according to thefourth embodiment of the present invention;

FIG. 5 is a plan view of a sheet convey apparatus according to the fifthembodiment of the present invention;

FIGS. 6A and 6B are side and plan views, respectively, showing aconventional sheet convey apparatus in a state of separating a sheet bysheet air blowers;

FIGS. 7A and 7B are side and plan views, respectively, showing theconventional sheet convey apparatus in a state of chucking the uppermostsheet by the first suction ports;

FIGS. 8A and 8B are side and plan views, respectively, showing theconventional sheet convey apparatus in a state of separating theuppermost sheet from sheets under it by a leveling foot;

FIGS. 9A and 9B are side and plan views, respectively, showing theconventional sheet convey apparatus in a state of transferring theuppermost sheet from first suction ports to second suction ports;

FIGS. 10A and 10B are side and plan views, respectively, showing theconventional sheet convey apparatus in a state of conveying theuppermost sheet by the second suction ports;

FIGS. 11A and 11B are side and plan views, respectively, showing theconventional sheet convey apparatus in a state of catching the uppermostsheet by holddown wheels and a sheet convey roll;

FIGS. 12A and 12B are side and plan views, respectively, showing theconventional sheet convey apparatus in a state of transferring theuppermost sheet by the holddown wheels and a sheet convey roll; and

FIGS. 13A and 13B are side and plan views, respectively, showing theconventional sheet convey apparatus in a state wherein an error occursafter the uppermost sheet is transferred from the first suction ports tothe second suction ports.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A sheet convey apparatus according to the first embodiment of thepresent invention will be described with reference to FIGS. 1A and 1B.Referring to FIG. 1A, a sheet convey apparatus 101 comprises a pileboard 111 on which a plurality of sheets 110 are to be stacked, a pairof first suction ports 112 (first chucking means) which are supported tobe movable in the widthwise direction of the sheets 110 stacked on thepile board 111, and a pair of second suction ports 113 (second chuckingmeans) which are supported to be movable in the back-and-forth direction(a direction of arrows A-B) of the sheets 110 staked on the pile board111. As shown in FIG. 1B, the pair of suction ports 113 are attached tothe two ends of a support shaft 114 extending in the widthwise direction(a direction perpendicular to the direction of the arrows A-B) of thesheets 110. The support shaft 114 is supported to be movable in thedirection of the arrows A-B through a cam shaft (not shown) which isaxially supported by a sucker frame 115 and driven to rotate by a motor,and a cam (not shown) which is axially mounted on the cam shaft. Suctionair is supplied to the suction ports 112 and 113 from an intake device(not shown) through a hose.

Sheet air blowers 116 serving as an air blowing member blow separationair to the sheets 110 stacked on the pile board 111 from behind so thestacked sheets 110 separate smoothly. When air is supplied from thesheet air blowers 116 to move a sheet 110 slightly upward, the movedsheet 110 is reliably chucked by the suction ports 112.

A leveling foot 117 serving as an air blowing member reciprocatesbetween a standby position and an operative position (FIG. 1A) andenters between an uppermost sheet 110A chucked by the suction ports 112and the sheets 110 under it to press the sheets 110. Simultaneously, theleveling foot 117 blows separation air to separate the uppermost sheet10A entirely from the sheets 110 under it. When the sheet which isconveyed as it is chucked by the suction ports 113 is released, holddownwheels 118 and a forwarding roll 119 catch the released sheet and feedit onto a feeder board 120.

The sheet convey apparatus 101 further comprises three third suctionports 121 a to 121 c (third chucking means) which are supported to bemovable in the back-and-forth direction (the direction of the arrowsA-B) of the sheets 110 stacked on the pile board 111 and chuck thetrailing edge of the sheet 110 transferred from the suction ports 112 toconvey it forward. The suction ports 121 a to 121 c are arrangedsubstantially on one straight line (on one straight line C) in thewidthwise direction of the suction ports 112 and sheets 110 and move inthe direction of arrows A-B integrally with the suction ports 113 at thesame speed. Thus, the suction ports 121 a to 121 c chuck a portion nearthe sheet widthwise direction of the trailing edge of the sheet 110chucked by the suction ports 112. The suction ports 121 a to 121 c alsocooperate with the suction ports 113 to convey the sheet 110 transferredfrom the suction ports 112 to the suction ports 113.

Three parallel arms 122 extend in the horizontal direction. One end ofeach arm 122 is fixed to the support shaft 114. The three third suctionports 121 a to 121 c are attached to the distal ends of the respectivearms 122 which extend toward the trailing edge (the direction of thearrow B) of the sheets 110 stacked on the pile board 111. That is, thesuction ports 121 a to 121 c are supported to integrally move in thedirections of the arrows A-B through the arms 122 to follow the suctionports 113. Therefore, the suction ports 121 a to 121 c move in thehorizontal direction at the same speed as that of the suction ports 113.

The suction ports 121 a to 121 c are located at substantially the sameheight as that of the suction ports 113. Suction air is supplied to thesuction ports 121 a to 121 c from an intake device (not shown) throughthe hose at the same timing as that for the suction ports 113. As shownin FIG. 1B, the suction port 121 a is arranged between the pair ofsuction ports 112 in the widthwise direction of the sheets 110. Thesuction ports 121 b and 121 c are arranged outside the pair of suctionports 112. Both the suction ports 121 a to 121 c and the pair of suctionports 112 are arranged on substantially one straight line C in thewidthwise direction of the sheets 110 when seen from the top. Theleveling foot 117 is arranged behind (in the direction of the arrow B),of the suction ports 121 a to 121 c and suction ports 112, the suctionport 121 a which is arranged at the center. The sheet air blowers 123are arranged behind the suction ports 121 b and 121 c which are arrangedon the two sides.

In this structure, the uppermost sheet 110A, the trailing edge of whichis chucked by the suction ports 112, is transferred from the suctionports 112 to the suction ports 113. At this time, suction air issupplied to the suction ports 121 a to 121 c to chuck the trailing edgeof the sheet 110A by the suction ports 121 a to 121 c. Immediately afterthis sheet transfer, the sheet air blowers 123 blow separation air whichseparates the uppermost sheet 110A from the sheets 110 under it.

In this manner, since the trailing edge of the uppermost sheet 110Awhich is transferred from the suction ports 112 to the suction ports 113is chucked by the suction ports 121 a to 121 c, a space where theseparation air passes is ensured under the uppermost sheet 110A. Thus,the separation air sufficiently separates the sheet, so the sheet 110Ais conveyed by the suction ports 113 and 121 a to 121 c without cominginto contact with a sheet 110 under it. Thus, the sheet 110A can beconveyed smoothly. Since the separation air blown from the leveling foot117 and sheet air blowers 123 does not pass above the sheet 110A, thetrailing edge of the sheet that has been fed out previously is not blownup by the separation air. Consequently, the sheet that has been fed outpreviously does not flutter or wave, so that poor sheet-feeding can beprevented.

FIG. 2 shows the second embodiment of the present invention. The sideview of the second embodiment and the side views of the third to fifthembodiments to be described hereinafter are substantially identical tothe side view of the first embodiment shown in FIG. 1B, and accordinglythese side views will be omitted. The identical members to those of thefirst embodiment are denoted by the same reference numerals, and adetailed description thereof will be omitted.

The second embodiment is different from the first embodiment in that thetwo side ones of three suction ports 121 a to 121 c and correspondingsheet air blowers 123 are omitted. More specifically, in a sheet conveyapparatus 151 according to the second embodiment, one suction port 121 aprovided in front of a leveling foot 117 is arranged between a pair ofsuction ports 112. One arm 122 extends which has one end fixed to thecenter of a support shaft 114. The suction port 121 a is attached to theother end of the arm 122. In this structure, when a sheet 110A is to betransferred from the pair of suction ports 112 to a pair of suctionports 113, its trailing edge is further chucked and held by the suctionport 121 a.

FIG. 3 shows the third embodiment of the present invention. The thirdembodiment is different from the first embodiment in that the centralone of three suction ports 121 a to 121 c is omitted. More specifically,in a sheet convey apparatus 161 according to the third embodiment, nosuction port is arranged in front of a leveling foot 117, and the pairof suction ports 121 b and 121 c are arranged in front of a pair ofsheet air blowers 123. Two arms 122 extend each of which has one endfixed to a corresponding end of a support shaft 114. Each of the pair ofsuction ports 121 b and 121 c is attached to the other end of thecorresponding one of the two arms 122. In this structure, when a sheet110A is to be transferred, its trailing edge is chucked and held bysuction ports 113 and the suction ports 121 b and 121 c.

FIG. 4 shows the fourth embodiment of the present invention. The fourthembodiment is different from the first embodiment in that another pairof suction ports are arranged outside the two outer ones of threesuction ports 121 a to 121 c. More specifically, in a sheet conveyapparatus 171 according to the fourth embodiment, in addition to a pairof suction ports 112, another pair of suction ports 112′ are arrangedoutside the suction ports 121 b and 121 c. In this structure, when asheet 110A is to be transferred, its trailing edge is chucked and heldby the suction ports 112, 112′, and 121 a to 121 c.

FIG. 5 shows the fifth embodiment of the present invention. The fifthembodiment is different from the first embodiment in that two more pairsof suction ports are arranged outside and inside the two outer ones ofthree suction ports 121 a to 121 c. More specifically, in a sheet conveyapparatus 181 according to the fifth embodiment, in addition to a pairof suction ports 112, another pair of suction ports 112′ are arrangedoutside the suction ports 121 b and 121 c, and still another pair ofsuction ports 112″ are arranged inside the suction ports 121 b and 121c. In this structure, when a sheet 110A is to be transferred, itstrailing edge is chucked and held by the suction ports 112, 112′, 112″,and 121 a to 121 c.

The respective embodiments described above are exemplified by an examplein which the suction ports 121 added to the pair of suction ports 112are arranged at various positions and an example in which the number ofthe suction ports 112 which originally forms a pair is increased. Notethat the present invention is not limited to these examples. It sufficesas far as the added suction ports 121 are arranged substantially on onestraight line in the sheet widthwise direction with respect to thesuction ports 112. While the sheet is exemplified as a sheet 110 in therespective embodiments, the present invention can also be applied to afilm-type sheet member.

In a structure as in the first and the third to fifth embodiments inwhich the sheet air blowers 123 are arranged behind the suction ports121 b and 121 c, the leveling foot 117 need not discharge air but maymerely serve as a sheet press.

As has been described above, according to the present invention, when asheet is to be transferred from the first suction ports to the secondsuction ports, a space is ensured under the sheet. Thus, separation aircan reliably prevent the sheet from coming into contact with anothersheet, so that the sheet can be conveyed smoothly. The trailing edge ofthe sheet that has been fed out previously is not blown up by theseparation air. Thus, the sheet that has been fed out previously doesnot flutter or wave, so that poor sheet-feeding can be prevented.

1. A sheet convey apparatus comprising: a pile board on which aplurality of sheets are to be stacked; air blowing means for supplyingair between a first sheet and a second sheet which are the first and thesecond when counted from an uppermost one of the sheets stacked on saidpile board, to separate the first sheet from the second sheet; firstchucking means, supported to be movable in a direction of sheetthickness, for chucking and holding a trailing edge of the separatedfirst sheet to lift upward the separated first sheet; second chuckingmeans, supported to be movable in a sheet back-and-forth direction, forchucking and holding a more sheet leading edge side than a portionchucked by said first chucking means of the first sheet transferred fromsaid first chucking means, and conveying the first sheet forward; andthird chucking means, supported to be movable in the sheetback-and-forth direction, for chucking and holding the trailing edge ofthe first sheet transferred from said first chucking means, andconveying the first sheet forward.
 2. An apparatus according to claim 1,wherein said second chucking means and said third chucking means moveintegrally at the same speed to convey the first sheet.
 3. An apparatusaccording to claim 1, wherein said first chucking means and said thirdchucking means are arranged substantially on one straight line in asheet widthwise direction.
 4. An apparatus according to claim 3, whereinthe trailing edge of the first sheet which is being conveyed by saidsecond chucking means is chucked and held by said third chucking meansto ensure a space between the first sheet and the second sheet where airfrom said air blowing means passes.
 5. An apparatus according to claim3, wherein said first chucking means and said third chucking means arearranged on a more sheet trailing edge side than said second chuckingmeans.
 6. An apparatus according to claim 5, wherein said first chuckingmeans comprises at least not less than two first suction ports which arearranged at a predetermined gap from each other in the sheet widthwisedirection, said second chucking means comprises at least not less thantwo second suction ports which are arranged at a predetermined gap fromeach other in the sheet widthwise direction, and said third chuckingmeans comprises at least one third suction port which is arranged in thevicinity in the sheet widthwise direction of said first suction ports.7. An apparatus according to claim 1, wherein said air blowing meanscomprises a sheet air blower which blows air to the first sheet frombehind the trailing edge of the first sheet, before said first chuckingmeans chucks the first sheet, to separate the first sheet from thesecond sheet.
 8. An apparatus according to claim 7, wherein said sheetair blower is arranged behind said pile board to correspond to saidfirst chucking means and said third chucking means.
 9. An apparatusaccording to claim 1, wherein said air blowing means further comprises aleveling foot which enters between the first sheet and the second sheet,after said first chucking means chucks the first sheet, to blow air to aspace formed therebetween.